arge intestine frequently. The rectum, sigmoid
flexure, caecum and colon are affected, and in this order, the
cylindrical-celled form being the most common. Carcinoma of the
peritoneum is generally colloid in character, and is often secondary to
growths in other organs. Cancer of the liver follows cancer of the
stomach and rectum in frequency of occurrence, and is relatively more
common in females than males. Secondary invasion of the liver is a
frequent sequel to gastric cancer. The pancreas occasionally is the seat
of cancerous growth.

Sarcomata are not so often met with in the digestive organs. When
present, they generally involve the peritoneum or the mesenteric glands.
The liver is sometimes attacked, the stomach rarely.

Benign tumours are not of common occurrence in the digestive organs.
Simple growths of the salivary glands, cysts of the pancreas and
polypoid tumours of the rectum are the most frequent.

Animal parasites.

The intestinal canal is the habitat of the majority of animal parasites
found in man. Frequently their presence leads to no morbid symptoms,
local or general; nor are the symptoms, when they do arise, always
characteristic of the presence of parasites alone. Discovery of their
bodies, or of their eggs, in the stools is in most instances the only
satisfactory proof of their presence. The parasites found in the bowel
belong principally to two natural groups, Protozoa and Metazoa. The
great class of the Protozoa furnish amoebae, members of Sporozoa and
Infusoria. The amoebae are almost invariably found in the large
intestine; one species, indeed, is termed _Amoeba coli_. The frequently
observed relation between attacks of dysentery and the presence of
amoebae in the stools has led to the proposition that an _Amoeba
dysenterica_ exists, causing the disease--a theory supported by the
detection of amoebae in the contents of dysenteric abscesses of the
liver. No symptoms of injury to health appear to accompany the presence
of Sporozoa in the bowel, while the species of Infusoria found in it,
the _Cercomonas_, and _Trichomonas intestinalis_, and the _Balantidium
coli_, may or may not be guilty of prolonging conditions within the
bowel as have previously set up diarrhoea.

The Metazoa supply examples of intestinal parasites from the classes
Annuloida and Nematoidea. To the former class belong the various
tapeworms found in the small intestine of man. They, like other
intestinal parasites, ar